Fiber optic probe having components and features that improve performance

ABSTRACT

A fiber optic probe is provided with a distal sampling end, a proximal end, and light delivery and collection paths therethrough. The probe includes a window disposed at the distal sampling end of the fiber optic probe, the window having a distal end and a proximal end. A lens is disposed at the proximal end of the window, the lens having a distal end, a proximal end, and an aperture. A light delivery optical fiber is provided having a distal end and a proximal end, the distal end being received by the lens aperture. An optical isolator provided within the lens aperture to optically isolate the light delivery path and the light collection path. A collection optical fiber is provided in optical communication with the fiber collection filter. The probe may include a lens collection filter disposed between the window and the lens.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 63/051,833 filed on Jul. 14, 2020, U.S. Provisional Application Ser.No. 63/152,937 filed on Feb. 24, 2021, and U.S. Provisional ApplicationSer. No. 63/179,418 filed on Apr. 25, 2021, the complete disclosures ofwhich are incorporated herein by reference in their entirety.

FIELD OF THE TECHNOLOGY

The technology relates to multi-fiber optical probes, more particularlyto multi-fiber optical probes having components and features thatimprove performance, and still more particularly to multi-fiber opticalprobes having component apertures and filters in the probe tip thatimprove a signal-to-noise ratio.

BACKGROUND OF THE TECHNOLOGY

Light-scattering spectroscopy entails illuminating a substance andanalyzing collected light rays that scatter back from the substance.Conventional fiber optic probes illuminate a substance and then guidecollected light rays into a spectrometer. Known fiber optic probesinclude an optical fiber with a first or proximal end connected to alaser source and a second or distal end that terminates at a probe tip.The optical fiber guides light rays emitted from a laser source to theprobe tip to illuminate the substance being examined. The fiber opticprobe includes a separate set of optical fibers with first or distalends located proximate to the probe tip and second or proximal endscoupled proximate to the spectrometer. The probe collects light raysscattered from the substance. The separate set of optical fibers guidesthe collected light rays from the probe tip to a spectrometer foranalysis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exploded view of a fiber optic probe having afilter forward of the lens, probe components with apertures, and anoptical isolator according to one example of the technology;

FIG. 2 illustrates an exploded view of a fiber optic probe having afilter forward of the lens, probe components with apertures, and anoptical isolator according to another example of the technology;

FIG. 3 illustrates an exploded view of a fiber optic probe having afilter forward of the lens, probe components with apertures, and anoptical isolator according to another example of the technology;

FIG. 4 illustrates an exploded view of a fiber optic probe having afilter forward of the lens and an alignment feature with aperturesaccording to one example of the technology;

FIG. 5A illustrates a Raman spectrum for a conventional fiber opticprobe according to one example of the technology;

FIG. 5B illustrates a Raman spectrum for an improved fiber optic probeaccording to one example of the technology;

FIG. 6A illustrates an end view of an optical fiber having a single ringconfiguration of collection fibers according to one example of thetechnology;

FIG. 6B illustrates an end view of an optical fiber having a multi-ringconcentric configuration of collection fibers according to one exampleof the technology;

FIG. 7 illustrates an exploded view of a fiber optic probe having afilter forward of the lens, probe components with apertures, an opticalisolator, and a multi-ring concentric configuration of collection fibersaccording to one example of the technology;

FIG. 8A illustrates a ray trace diagram of a fiber optic probeillustrated in FIG. 7 having a filter forward of the lens, probecomponents with apertures, an optical isolator, and a multi-ringconcentric configuration of collection fibers according to one exampleof the technology;

FIG. 8B illustrates a ray trace diagram of a fiber optic probeillustrated in FIG. 7 having a filter forward of the lens, probecomponents with apertures, an optical isolator, and a multi-ringconcentric configuration of collection fibers according to one exampleof the technology;

FIG. 9 illustrates an exploded view of a fiber optic probe havingalternative restricted windows, a filter forward of the lens, probecomponents with apertures, an optical isolator, and a multi-ringconcentric configuration of collection fibers according to one exampleof the technology;

FIG. 10A illustrates a ray trace diagram of a fiber optic probeillustrated in FIG. 9 having alternative restricted windows, a filterforward of the lens, probe components with apertures, an opticalisolator, and a multi-ring concentric configuration of collection fibersaccording to one example of the technology;

FIG. 10B illustrates a ray trace diagram of a fiber optic probeillustrated in FIG. 9 having alternative restricted windows, a filterforward of the lens, probe components with apertures, an opticalisolator, and a multi-ring concentric configuration of collection fibersaccording to one example of the technology;

FIG. 11 illustrates an exploded view of a fiber optic probe having afilter forward of the lens, a total internal reflectance lens, probecomponents with apertures, an optical isolator, and a multi-ringconcentric configuration of collection fibers according to one exampleof the technology;

FIG. 12 illustrates a ray trace diagram of a fiber optic probeillustrated in FIG. 11 having a filter forward of the lens, a totalinternal reflectance lens, probe components with apertures, an opticalisolator, and a multi-ring concentric configuration of collection fibersaccording to one example of the technology;

FIG. 13 illustrates a perspective view of a lens with one active facetand an aperture according to one example of the technology;

FIG. 14 illustrates a perspective view of a lens with two active facetsand an aperture according to one example of the technology;

FIG. 15 illustrates a perspective view of an alternative lens with twoactive facets and an aperture according to one example of thetechnology;

FIG. 16 illustrates a perspective view of a lens with four active facetsand an aperture according to one example of the technology;

FIG. 17A illustrates a bottom view of a lens structure having multiplelenslets and an alignment pin according to one example of thetechnology;

FIG. 17B illustrates a side view of a lens structure having multiplelenslets and an alignment pin according to one example of thetechnology;

FIG. 18 illustrates an exploded view of a fiber optic probe having afilter forward of the lens, probe components with apertures, and aninternal calibration sample according to one example of the technology;

FIG. 19 illustrates an external calibration system according to oneexample of the technology; and

FIG. 20 illustrates construction of a two-ring concentric configurationof collection fibers according to one example of the technology.

DETAILED DESCRIPTION OF THE TECHNOLOGY

It will be appreciated that for simplicity and clarity of illustration,where appropriate, reference numerals may be repeated among thedifferent figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the examples described herein. However, itwill be understood by those of ordinary skill in the art that theexamples described herein may be practiced without these specificdetails. In other instances, methods, procedures, and components havenot been described in detail so as not to obscure the related relevantfeature being described. Also, the description is not to be consideredas limiting the scope of the examples described herein. The drawings arenot necessarily to scale and the proportions of certain parts may havebeen exaggerated to better illustrate details and features of thepresent disclosure. Those skilled in the art with access to theteachings provided herein will recognize additional modifications,applications, and examples within the scope thereof and additionalfields in which the technology would be of significant utility.

Unless defined otherwise, technical terms used herein have the samemeaning as is commonly understood by one of ordinary skill in the art towhich this disclosure belongs. The terms “first,” “second,” and thelike, as used herein do not denote any order, quantity, or importance,but rather are used to distinguish one element from another. Also, theterms “a” and “an” do not denote a limitation of quantity, but ratherdenote the presence of at least one of the referenced items. The term“or” is meant to be inclusive and means either, any, several, or all ofthe listed items. The terms “comprising,” “including,” and “having” areused interchangeably in this disclosure. The terms “comprising,”“including,” and “having” mean to include, but are not necessarilylimited to the things so described.

The terms “connected” and “coupled” can be such that the objects arepermanently connected, releasably connected, or linked. The term“substantially” is defined to be essentially conforming to the thingthat it “substantially” modifies, such that the thing need not be exact.For example, substantially 2 inches (2″) means that the dimension mayinclude a slight variation.

What is needed is a fiber optic probe having an improved probe tipconstruction or improved probe tip components designed for spectroscopyapplications, including Raman spectroscopy applications. According toone example, an improved probe tip construction includes a novel andnon-obvious design or arrangement of probe tip components. For example,a lens filter component may be positioned forward of a lens componenthaving refractive or reflective surfaces. Throughout this disclosure,forward of a component in the context of a fiber optic probe meanscloser to a distal end of the fiber optic probe.

According to one example, the fiber optic probe may include a probe tipconstruction that optically isolates the excitation laser light fromprobe components associated with the collection path. For example, theexcitation laser light may be optically isolated and may exit the probetip at or forward of the lens refractive or reflective surfacesassociated with the collection path. According to one example, theexcitation laser light may be optically isolated by blocking lightpenetration into substrates located adjacent to the emission waveguideor emission fiber. According to one example, one or more emission fibersmay be inserted into or through apertures formed in probe tipcomponents. According to one example, the apertures may form an opticalisolator between the excitation light path and the collection lightpath. According to one example, the emission or light delivery fibersmay be optically isolated by placing a light blocking structure such asa physical barrier, a metal tube, or the like, within apertures formedin probe tip components. Alternatively, or additionally, the emission orlight delivery fibers may be optically isolated from the collection pathby lining the apertures with a light blocking coating such as a blackpolymer, a black filled epoxy, or the like.

According to one example, the excitation laser light may be opticallyisolated from a lens component by forming an aperture or orifice in thelens that receives the emission fiber therethrough. In other words, theemission fiber may be inserted into or through the lens aperture.According to one example, the aperture may be lined with a lightblocking coating that prevents the laser light from penetrating throughthe aperture sidewall. For example, the light blocking coating may beprovided along a circumference of the aperture. Alternatively, theexcitation laser light may be optically isolated from a lens componentby placing a light blocking structure into the aperture that receivesthe emission fiber therethrough. The technology supports various lightbarriers that block, prevent, or optically isolate laser light frominteracting with surrounding materials.

According to one example, the fiber optic probe may include a lens withone or more surfaces or facets that provide flat faces on workingportions of the lens. In contrast, conventional lens structuresgenerally include smooth or continuous spherical or hemisphericalsurfaces on working portions of the lens. According to one example, theone or more lens facets may cause light rays impinging upon the workingportion of the lens to refract or totally internally reflect. Accordingto another example, the technology may include a lens component thatcombines flat facets and standard or conventional smooth or continuousspherical or hemispherical surfaces. According to one example, thefacets may be oriented and positioned relative to the optical fibers toappropriately guide the excitation light rays or the collection lightrays. For example, the facets may guide the excitation light rays toimpinge the sample or substance being examined. Furthermore, the facetsmay guide collection light rays that are scattered, reflected, oremitted from the sample or substance into a spectrometer. According toone example, the lens component may include multiple lens components ormultiple lens elements having air gaps. Alternatively, the lenscomponent may include a single lens component with one or more facets.

According to one example, the technology provides fiber optic probeshaving several optical fibers and an improved lens structure that offersa high numerical aperture. In optics, a numerical aperture is adimensionless number that characterizes a range of angles over which adevice can emit or receive light. The technology provides fiber opticprobes with lens components having one or more facets that offer maximumphoton collection needed for Raman spectroscopic medical applications.

According to one example, the fiber optic probe may include collectionfibers arranged in a multi-ring configuration that surround the emissionor light delivery fibers. According to one example, the multi-ringconfiguration may enable data collection from different depths relativeto a sample surface. According to one example, the collection fibersassociated with a ring located closer to the emission fiber may collectdata from an area deeper in a sample. In contrast, collection fibersassociated with a ring located farther from the emission fiber maycollect data from an area closer to a sample surface. According to oneexample, the fiber optic probe may include a lens that directs lightrays collected from different depths within a sample to one or more ofthe several collection fiber rings.

According to one example, a computer system coupled to a spectrometermay capture and analyze spectral data associated with the fiber opticprobe. According to one example, the computer system may separatelyanalyze spectral data associated with the one or more optical fiberrings. Accordingly, the computer system may analyze spectral dataseparately for optical fiber rings associated with different depthmeasurements. According to one example, the computer system maymanipulate the spectral data using mathematical operations. For example,the computer system may add, subtract, multiply, or perform othermathematical operations on the spectral data associated with differentoptical rings.

According to one example, the fiber optic probe may include acalibration fiber that internally originates a calibration signal.According to one example, generating an internal calibration signal maysimplify, expedite, and eliminate drawbacks typically associated withobtaining an external calibration signal. According to one example, theinternal calibration signal may be employed in medical settings thatrequire a sterilized calibration source or sample. According to oneexample, a calibration fiber may include a sealed or sterilizedcalibration sample at the probe tip.

Applications for the technology may include optical scanners and probesused during medical operations to provide essential molecularinformation, optical scanners and probes used to obtain pathologyinformation, optical scanners and probes used to provide surgicalguidance or additional information associated with tissue removal, anddiagnostic applications, among other applications. The technology offersimproved performance and reduced acquisition time during real-timemedical procedures or surgeries, when acquisition time is of theessence.

According to one example, the optical technology described herein may beused in conjunction with other imaging technology such as magneticresonance imaging (MRI) technology or the like. An MM scan is a medicalimaging technique that uses a magnetic field and computer-generatedradio waves to create detailed images of organs and body tissue.According to one example, MRI scans generate soft tissue contrast thatis used to detect a cancer tumor or other abnormal tissue. However, MMtechnology has limited resolution meaning it may not be able to detectabnormal tissue occurring in low density. In contrast, the opticaltechnology described herein is capable of detecting the presence of asingle atom or molecule of a substance. Cancer cells are physicallydifferent from healthy cells. Thus, the optical technology describedherein is capable of discovering a single cancer cell within anotherwise healthy organ.

According to one example, the optical technology described herein may beused with other imaging systems to enhance overall system performance.For example, images associated with chemical data generated by theoptical technology described herein may be overlayed on imagesassociated with electro-magnetic data generated by an MM system data toenhance overall system performance. According to one example, known MMtechnology may generate a three-dimensional (3-D) image of the humanbrain with position data. The optical technology described herein maygenerate chemical data obtained from known depths relative to a knownreference point within the human brain. According to one example, theenhanced system may detect and calculate a location in 3-D space of acancer cell by overlaying the chemical data associated with a knowndepth and the 3-D location data associated with the electro-magneticdata.

FIG. 1 illustrates an exploded view of a probe tip for a fiber opticprobe 100 having a lens filter, probe components with apertures, and anoptical isolator according to one example of the technology. Accordingto one example, the fiber optic probe 100 may include several componentssuch as a window 101, a lens filter 102 having an aperture 103, a lens104 with an aperture 105, a collection fiber filter 106 associated withone or more rings of collection fibers 107, the collection fiber filter106 having an aperture 108, an emission fiber filter 109 associated withone or more emission fibers 110, and a needle tube 111 that preventslight transfer proximate to the probe tip between the emission fibers110 and the collection fibers 107. According to one example, thecomponents include a distal end located forward or upstream of the probeand a proximal end located downstream of the probe. According to oneexample, the distal and proximal ends are provided at componentinterfaces. According to one example, the distal and proximal ends maybe positioned substantially perpendicular to the light path. Accordingto one example, a carbon black filled epoxy may be used in place of theneedle tube 111. According to one example, the component apertures, theneedle tube 111, the carbon black filled epoxy, and the like, arereferred to as optical isolators herein since they may optically isolatethe light delivery path and the light collection path. According to oneexample, the lens filter 102, the lens 104, and the collection fiberfilter 106 may be annular or donut-shaped components. According to oneexample, the emission fiber filter 109 and the emission fiber 110 may beinserted into or may pass through corresponding apertures in thedonut-shaped components when the fiber optic probe 100 is assembled.According to one example, the filter components may include dielectricfilter components with the filter material deposited on a substrate.According to one example, an anti-reflective (AR) coating may be appliedto probe components such as the lens to minimize reflective losses.

According to one example, the fiber optic probe 100 may include a fiberalignment holder 113 that defines a fiber pattern on an end face 114.For example, FIG. 1 illustrates a centrally positioned emission fiber110 surrounded by a circular or revolver pattern of collection fibers107. FIG. 6A illustrates a top view of this concentric single ring 701configuration. According to one example, the apertures 103,105,108defined in the fiber optic components may be formed to substantiallyalign with the position of the emission fiber 110 in the fiber alignmentholder 113.

According to one example, the fiber alignment holder 113 with the endface 114 may be employed to secure the collection fibers 107 and theemission fibers 110 in a desired configuration. According to oneexample, the end face 114 may include one or more apertures adapted tosecure the collection fibers 107 and the emission fibers 110 in adesired configuration. According to one example, the end face 114 mayinclude a plurality of apertures that receive the collection fibers 107therethrough. According to one example, the end face 114 may include alarge central aperture that receives the emission fibers 110 therein.According to one example, the apertures may be patterned to secure theoptical fibers in any desired arrangement or configuration such as aring-shaped arrangement, a linear arrangement, or the like. According toone example, the apertures may be arranged in a random or specificformation such as a single ring pattern, a multi-ring pattern, a singleline pattern, multi-line pattern, or the like. According to one example,the apertures may be provided in any combination of an individual fiberpattern or a group pattern such as a ring pattern, a line pattern, orthe like.

According to one example, a shape of the probe components such as thelens, the facets, the filters, or the like, may dictate or determine theaperture requirements and the optical fiber arrangement. According toone example, the collection and emission fibers 107,110 may be insertedinto corresponding apertures in the end face 114 and may be secured inplace to render a desired optical fiber arrangement. For example, thecollection and emission fibers 107,110 may be secured by a friction fit,an epoxy, or the like. According to one example, the collection andemission fibers 107,110 may be inserted individually into correspondingapertures of the end face 114. Additionally, or alternatively, thecollection and emission fibers 107,110 may be bundled or groupedtogether for insertion into corresponding apertures of the end face 114.For example, FIG. 1 illustrates a group of emission fibers 110 that arebundled together in a single aperture provided in the end face 114.Furthermore, FIG. 1 illustrates collection fibers 107 insertedindividually into multiple apertures provided in the end face 114. Inthis way, the fiber alignment holder 113 and the end face 114 may beformed to align or match a pattern of the collection and emission fibers107,110 with a geometry of the lens or facets.

According to one example, the collection and emission fibers 107,110 maybe inserted into or may pass through corresponding apertures in the endface 114 and may be positioned relative to other components of the fiberoptic probe 100 as desired. For example, the collection and emissionfibers 107,110 may be inserted into or may pass through correspondingapertures in the end face 114 and may be positioned to abut against thelens 104 or the filters 106,109. According to another example, thecollection and emission fibers 107,110 may be inserted through thecorresponding apertures in the end face 114 and may be offset a desireddistance from the lens structure 104 or the filters 106,109. Accordingto one example, the collection and emission fibers 107,110 may befixedly secured to the end face 114, to the lens 104, or the filters106,109 such as by epoxy or the like. Any epoxy applied to lighttransmission interfaces should be a clear optical epoxy to allowefficient passage of light rays. According to one example, thecollection fibers 107 may be secured by epoxy and polished. For example,the collection fibers 107 may be polished together. According to oneexample, the emission fibers 110 may be polished separately from thecollection fibers 107. According to one example, an assembly thatincludes the emission fibers 110 may be inserted through thecorresponding aperture in end face 114. According to one example, thecollection fibers 107 initially may be secured to correspondingapertures of the end face 114 and subsequently the emission fibers 110may be secured to an aperture of the end face 114. Next, the collectionfiber filter 106 may be attached, followed by the lens 104 or the window101. According to one example, the fiber alignment holder 113 and theend face 114 may be formed using various techniques. For example, thefiber alignment holder 113 and the end face 114 may be formed bymachining, 3D printing, molding, or the like. According to one example,the end face 114 may include apertures having different shapes such asslots. According to one example, the slots may be dimensioned such thata width of the slot is substantially equivalent to a diameter of anoptical fiber. According to one example, the slots may be configured toreceive multiple optical fibers in order to form multi-fiberconfigurations such as radial lines, curved lines, geometrical shapes,or the like.

According to one example, the lens filter 102 may include a long-pass ora notch filter. According to one example, the lens filter 102 may be adonut-shaped long-pass or notch filter. The lens filter 102 is designedto decrease a light intensity before the collected light rays interactwith the lens material or other probe materials. Accordingly, the lensfilter 102 allows the optic probe 100 to minimize noise signalgeneration while employing virtually any lens or substrate material.Without inclusion of the lens filter 102, the collected light rays maycreate noise signals such as unwanted peaks, interference, or backgroundfluorescence when impinging the probe components. For example, thecollected light rays may cause probe components to fluoresce whenimpinged. The noise signals, including unwanted peaks, interference, orbackground fluorescence, may be added to or superimposed over spectra ofa desired specimen.

According to one example, this new probe design includes a lens filter102 positioned forward or upstream of the lens 104 that decreases orflattens background interference or noise signals attributed tocollected light rays impinging on the lens 104. According to oneexample, minimizing background interference or noise signals attributedto the lens 104 may increase a signal-to-noise ratio (SNR) for a system.Still further, placing the lens filter 102 forward or upstream of otherprobe components may decrease or flatten background interference ornoise signals attributed to collected light rays that impinge downstreamprobe components. According to one example, minimizing backgroundinterference or noise signals attributed to one or more probe componentsincreases a SNR of the system.

According to another example, providing optical isolators between thelight delivery path and the light collection path such as an aperture103 in the lens 102 and apertures 105,108 in the other probe componentsmay substantially eliminate noise signals such as unwanted peaks,interference, or background fluorescence caused by the excitation laserimpinging upon these components. Accordingly, providing apertures103,105,108 in the various probe components increases a SNR of thesystem and minimizes negative influences or crosstalk attributed to theexcitation laser. In this way, the SNR of the system may be increasedbased upon a combination of providing one or more apertures 103,105,108in the probe components and providing the lens filter 102 forward of thelens 104 or other probe components. One of ordinary skill in the artwill readily appreciate that the one or more filters may be eliminatedfrom the fiber optic probe 100 depending on the spectroscopicapplication.

While the component apertures 103,105,108 improve a SNR of the system,the air gap formed between a circumference of the emission fiber 110 anda circumference of the component apertures 103,105,108 may introduceunfavorable characteristics to the probe tip such as reduced rigidity orcrosstalk originating from the emission fibers 110 to the collectionfibers 107. According to one example, crosstalk may occur when emissionlight rays disperse or leak at material interfaces. A remedy includesfilling the air gap, which forms an optical isolator between the lightdelivery path and the light collection path. For example, the air gapmay be filled with a material such as a waveguide or non-waveguidematerial. According to one example, a carbon black filled epoxy may beapplied to a perimeter of the one or more apertures 103,105,108 as anadditional optical isolator between the light delivery path and thelight collection path. According to one example, a cylindrical-shapedcore material such as fused silica or magnesium fluoride may be insertedinto the air gap as yet another optical isolator between the lightdelivery path and the light collection path and to increase probe tiprigidity. According to one example, the carbon black filled epoxy may beapplied to a perimeter of the one or more apertures 103,105,108 and thecylindrical-shaped core material may be inserted into the air gap toprovide multiple optical isolators between the light delivery path andthe light collection path. For example, the cylindrical-shaped corematerial or tube may be friction fitted or bonded to an inside perimeterof the one or more apertures 103,105,108.

According to one example, the carbon black lined apertures provideoptical isolation by absorbing stray light, while the cylindrical-shapedcore material adds rigidity and additional optical isolation. Accordingto one example, the carbon black lined apertures prevent the excitationlaser light from entering the light collection path. Stated differently,the carbon black lined apertures block the excitation laser light frompenetrating into adjacent materials. Furthermore, the carbon black linedapertures block the collected light from penetrating into the emissionfiber 110 or light delivery path. Accordingly, the technology providesminimal crosstalk between the excitation laser light and the collectedlight rays, which results in an improved SNR for the collected lightsignals. One of ordinary skill in the art will readily appreciate thatother techniques may be employed to fill the air gap formed between thecircumference of the emission fiber 110 and the circumference of thecomponent apertures 103,105,108.

According to one example, the fiber optic probe 100 may include thewindow 101 as an outer component of the probe tip that may directlycontact a substance during testing. According to one example, athickness of the window 101 may be selected so that the distal end ispositioned at or proximate to a maximum intensity area defined by anintersection of the emission light rays and the collection light rays.According to one example, the fiber optic probe 100 may be maintained acertain distance from the specimen or substance during use. According toone example, the window 101 may be constructed of one or more materialssuch as magnesium fluoride (MgF₂), fused silica, sapphire, or the like,that are transparent to light rays over a wide range of wavelengths andavoid generating spectral interference or noise signals. According toone example, the window 101 may be employed to protect the probecomponents. According to one example, the window 101 may be employedduring Raman or other spectroscopic techniques to generate a referencepeak or spectra during calibration.

According to one example, the window 101 may be formed by depositing oradhering a thin layer of material such as diamond, sapphire, or the likeon either side of the window 101. For example, the thin layer ofmaterial may be adhered on either side of the window 101 using epoxy orthe like. According to another example, the thin layer of material maybe sandwiched between two window pieces to protect the calibrationlayer. According to one example, the reference peak or spectra may beused to calibrate or normalize probes or full systems, including lasers,probes, spectrometers, detectors, to each other. According to oneexample, the material and window or layer thickness may be selected toenhance durability, minimize spectral interference, enhance lightintensity at the sample, and improve calibration. According to oneexample, the material and window or layer thickness may be selected toenhance spectral signal acquisition for materials or samples beinginvestigated. According to one example, a magnesium fluoride window maybe used alone or in a layer to improve calibration for Ramanspectroscopy. One of ordinary skill in the art will readily appreciatethat the window 101 may be constructed of any materials that aresubstantially transparent to light over a wide range of wavelengths andavoid generating spectral interference, noise signals, or a window Ramansignal that may overshadow a sample Raman signal.

According to one example, the fiber optic probes may be modified such asby providing different component orientations, different componentarrangements, different lens styles, different component shapes, or thelike. FIG. 2 illustrates an exploded view of an alternative probe tipfor a fiber optic probe 200 having a lens filter, optical isolators, andprobe components with apertures according to one example of thetechnology. Fiber optic probe 200 is similar to fiber optic probe 100illustrated in FIG. 1, except an orientation of the lens 204 is flippedcompared to the orientation of lens 104. Accordingly, an air interfaceis provided proximate to a proximal end of the lens filter 202 in FIG.2. In contrast, an air interface is provided proximate to the distal endof the collection fiber filter 106 in FIG. 1. According to one example,the components include a distal end located forward or upstream of theprobe and a proximal end located downstream of the probe. According toone example, the distal and proximal ends are provided at componentinterfaces. According to one example, the distal and proximal ends maybe positioned substantially perpendicular to the light path.

According to one example, the lens 204 includes an aperture 205 thatreceives one or more emissions fibers 110 therethrough. According to oneexample, a lens filter 202 includes an aperture 203 that receives one ormore emissions fibers 110 therethrough. According to one example, theapertures 203,205 are optical isolators between the light delivery pathand the light collection path. According to one example, the lens filter202 is designed to compensate for qualities and characteristics of thelens 204, the other probe components, or the collected light. Forexample, the lens filter 202 may be designed to decrease a lightintensity before the collected light rays impinge a lens material orother probe materials. Accordingly, the lens filter 202 allows the fiberoptic probe 200 to minimize noise signal generation while employingvirtually any lens or substrate material. Without inclusion of the lensfilter 202, the collected light rays may create noise signals such asunwanted peaks, interference, or background fluorescence when impingingthe probe components. For example, the collected light rays may causeprobe components to fluoresce when impinged. The noise signals,including unwanted peaks, interference, or background fluorescence, maybe added to or superimposed over spectra of a desired specimen.

According to one example, the probe design includes a lens filter 202positioned forward or upstream of the lens 204 to decrease or flattenbackground interference or noise signals attributed to collected lightrays impinging on the lens 204. According to one example, minimizingbackground interference or noise signals attributed to the lens 204 mayincrease a SNR for a system. Still further, placing the lens filter 202forward or upstream of other probe components may decrease or flattenbackground interference or noise signals attributed to collected lightrays that impinge downstream probe components. According to one example,minimizing background interference or noise signals attributed to one ormore probe components increases a SNR of the system.

According to one example, the lens filter 202, the lens 204, and thecollection fiber filter 206 may be donut-shaped components. According toone example, the emission fiber filter 109 and the emission fiber 110may be inserted into or pass through the donut-shaped components whenthe fiber optic probe 200 is assembled. FIG. 2 illustrates a centrallypositioned emission fiber 110 surrounded by a circular pattern ofcollection fibers 107. FIG. 6A illustrates a top view of this concentricsingle ring 701 configuration. According to one example, the apertures203,205,208 defined in the fiber optic components may be formed tosubstantially align with the position of the emission fiber 110.According to one example, the component shapes and the componentarrangements illustrated in FIG. 2 may be substantially similar to theprobe components illustrated in FIG. 1. Accordingly, the componentdetails described with respect to FIG. 1 are not repeated with respectto FIG. 2.

FIG. 3 illustrates an exploded view of an alternative probe tip for afiber optic probe 300 having a lens filter, probe components withapertures, an optical isolator, and a side-by-side arrangement of thecollection fibers 307 and the emission fibers 310 according to oneexample of the technology. According to one example, the emission fiber310 may be positioned at an edge of the fiber alignment holder 313.According to one example, the collection fibers 107 may be positionedthroughout the remaining portion of the fiber alignment holder 313.According to one example, the probe components may include apertures oroptical isolators formed to substantially align with the position of theemission fibers 310. According to one example, the fiber optic probe 300may include several components such as a window 101, a lens filter 302having an aperture 303, a lens 304 with an aperture 305, a collectionfiber filter 306 associated with one or more rings of collection fibers307, the collection fiber filter 306 having an aperture 308, an emissionfiber filter 309 associated with one or more emission fibers 310, and aneedle tube 311 that prevents light transfer proximate to the probe tipbetween the emission fibers 310 and the collection fibers 307. Accordingto one example, a carbon black filled epoxy may be used in place of theneedle tube 311. According to one example, the components include adistal end located forward or upstream of the probe and a proximal endlocated downstream of the probe. According to one example, the distaland proximal ends are provided at component interfaces. According to oneexample, the distal and proximal ends may be positioned substantiallyperpendicular to the light path. According to one example, the componentapertures, the needle tube 311, the carbon black filled epoxy, and thelike, are referred to as optical isolators herein since they mayoptically isolate the light delivery path and the light collection path.

According to one example, the lens filter 302, the lens 304, and thecollection fiber filter 306 may include apertures 303,305,308,respectively, that are formed to substantially align with a position ofthe emission fibers 310 in the fiber alignment holder 313. For example,the apertures 303,305,308 may be provided along an edge of the lensfilter 302, the lens 304, and the collection fiber filter 306,respectively. According to one example, the apertures 303,305,308 may beformed in non-active portions of the probe components. With reference toFIG. 3, the non-active portions may be located proximate to the emissionfibers 310. Alternatively, the active portions of the probe componentsmay be located along the collection path in optical communication withthe collection fibers 307. For example, the aperture 305 may be formedin a non-active portion of the lens 304, while the active portions ofthe lens 304 may be positioned in optical communication with thecollection fibers 307. For example, the active portions of the lens 304may correspond to refractive or reflective surfaces. According to oneexample, the emission fiber filter 309 and the emission fiber 310 may beinserted into or may pass through corresponding apertures in the probecomponents when the fiber optic probe 100 is assembled. For example, theemission fiber 310 may be placed on a side or refractive portion of thelens 304.

According to one example, the lens filter 302 is designed to compensatefor undesired qualities and characteristics of the lens 304, the otherprobe components, or the collected light rays. For example, the lensfilter 302 may be designed to decrease a light intensity before thecollected light rays interact with the lens material or other probematerials. Accordingly, the lens filter 302 allows the optic probe 300to minimize noise signal generation while employing virtually any lensor substrate material. Without inclusion of the lens filter 302, thecollected light rays may create noise signals such as unwanted peaks,interference, or background fluorescence when impinging the probecomponents. For example, the collected light rays may cause probecomponents to fluoresce when impinged. The noise signals, includingunwanted peaks, interference, or background fluorescence, may be addedto or superimposed over spectra of a desired specimen.

According to one example, the probe design includes a lens filter 302positioned forward or upstream of the lens 304 to decrease or flattenbackground interference or noise signals attributed to collected lightrays impinging on the lens 304. According to one example, minimizingbackground interference or noise signals attributed to the lens 304 mayincrease a SNR for a system. Still further, placing the lens filter 302forward or upstream of other probe components may decrease or flattenbackground interference or noise signals attributed to collected lightrays that impinge downstream probe components. According to one example,minimizing background interference or noise signals attributed to one ormore probe components increases a SNR of the system.

With respect to FIGS. 2 and 3, while the component apertures203,205,208/303,305,308 improve a SNR of the system, the air gap formedbetween a circumference of the emission fiber 110/310 and acircumference of the component apertures 203,205,208/303,305,308 mayintroduce unfavorable characteristics to the probe tip such as reducedrigidity or crosstalk originating from the emission fibers 110/310 tothe collection fibers 107/307. According to one example, crosstalk mayoccur when emission light rays disperse or leak at material interfaces.A remedy includes filling the air gap, which forms an optical isolatorbetween the light delivery path and the light collection path. Forexample, the air gap may be filled with a material such as a waveguideor non-waveguide material. According to one example, a carbon blackfilled epoxy may be applied to a perimeter of the one or more apertures203,205,208/303,305,308 as an additional optical isolator between thelight delivery path and the light collection path. According to oneexample, a cylindrical-shaped core material such as silica or magnesiumfluoride may be inserted into the air gap as yet another opticalisolator between the light delivery path and the light collection pathand to increase probe tip rigidity. According to one example, the carbonblack filled epoxy may be applied to a perimeter of the one or moreapertures 203,205,208/303,305,308 and the cylindrical-shaped corematerial may be inserted into the air gap to provide multiple opticalisolators between the light delivery path and the light collection path.For example, the cylindrical-shaped core material or tube may befriction fitted or bonded to an inside perimeter of the one or moreapertures 203,205,208/303,305,308.

According to one example, the carbon black lined apertures provideoptical isolation by absorbing stray light, while the cylindrical-shapedcore material adds rigidity and additional optical isolation. Accordingto one example, the carbon black lined apertures prevent the excitationlaser light from entering the light collection path. Stated differently,the carbon black lined apertures block the excitation laser light frompenetrating into adjacent materials. Furthermore, the carbon black linedapertures block the collected light from penetrating into the emissionfiber 110/310 or light delivery path. Accordingly, the technologyprovides minimal crosstalk between the excitation laser light and thecollected light rays, which results in an improved SNR for the collectedlight signals. One of ordinary skill in the art will readily appreciatethat other techniques may be employed to fill the air gap formed betweenthe circumference of the emission fiber 110/310 and the circumference ofthe component apertures 203,205,308/303,305,308.

FIG. 4 illustrates an exploded view of another alternative probe tip fora fiber optic probe 400 having a lens filter, alignment featurecomponents with apertures, and a side-by-side arrangement of thecollection fibers 307 and the emission fibers 310 according to oneexample of the technology. According to one example, the emission fiber310 may be positioned at an edge of the fiber alignment holder 313.According to one example, the collection fibers 307 may be positionedthroughout the remaining portion of the fiber alignment holder 313.According to one example, the probe components 402,404,406 may becoupled to alignment feature components 411,412,413 having apertures403,405,408. In this way, the probe components themselves do not requireapertures and the alignment features may include desired light blockingcharacteristics. According to one example, the emission fiber filter 309and the emission fiber 310 may be inserted into or may pass throughcorresponding apertures in the alignment feature components 411,412,413when the fiber optic probe 400 is assembled. According to one example,the components include a distal end located forward or upstream of theprobe and a proximal end located downstream of the probe. According toone example, the distal and proximal ends are provided at componentinterfaces. According to one example, the distal and proximal ends maybe positioned substantially perpendicular to the light path.

According to one example, the air gap formed between a circumference ofthe emission fiber 310 and a circumference of the apertures 403,405,408may introduce unfavorable characteristics to the probe tip such asreduced rigidity or crosstalk originating from the emission fibers 310to the collection fibers 307. According to one example, crosstalk mayoccur when emission light rays disperse or leak at material interfaces.A remedy includes filling the air gap, which forms an optical isolatorbetween the light delivery path and the light collection path. Forexample, the air gap may be filled with a material such as a waveguideor non-waveguide material. According to one example, the air gap may befilled with a gap filler such as epoxy, adhesive, or other gap filler.Furthermore, a cylindrical-shaped core material such as silica ormagnesium fluoride may be inserted into the air gap. For example, thecylindrical-shaped core material or tube may be friction fitted orbonded to an inside perimeter of the one or more apertures 403,405,408.

According to one example, the probe components 402,404,406 may becoupled to the alignment features 411,412,413 in any of various ways.For example, the probe components may be coupled to the alignmentfeatures using chemical bonding such as epoxy, glue, or the like.Alternatively, the probe components may be coupled to the alignmentfeatures using mechanical bonding such as fasteners, tongue and groove,or the like. One of ordinary skill in the art will readily appreciatethat several techniques may be employed to couple the probe componentsand the alignment features together.

According to one example, the fiber optic probe 400 may include severalcomponents such as a window 101, a lens filter 402, a lens filteralignment feature 411 having an aperture 403, a lens 404, a lensalignment feature 412 with an aperture 405, a collection fiber filter406 associated with one or more rings of collection fibers 307, acollection fiber alignment feature 413 having an aperture 408, anemission fiber filter 309 associated with one or more emission fibers310, and a needle tube 311 that prevents light transfer proximate to theprobe tip between the emission fibers 310 and the collection fibers 307.According to one example, a carbon black filled epoxy may be used inplace of the needle tube 311. According to one example, the probecomponents 402,404,406 may be constructed without apertures. Accordingto one example, the probe components 402,404,406 may be shaped tomechanically couple to the alignment features 411,412,413 and to fitwithin the contours of the probe tip. According to one example, thealignment features 411,412,413 may be configured to optically isolatethe collection light path and the excitation light path. According toone example, the alignment features 411,412,413 may be constructed of alight blocking substrate such as black plastic, black epoxy, a metaltube, a physical light block, or the like.

According to an alternative example, the probe tip may define an orificeor aperture that receives emission fibers therein (not shown) such thatnone of the probe components, including the alignment features, requirean aperture to receive the emission fibers 310. According to oneexample, the emission fiber 310 may pass through an orifice or aperturedefined in a probe body that forms the probe tip. According to oneexample, the emission fiber 310 may be affixed to the probe body usingepoxy, glue, or the like. Alternatively, or additionally, the collectionfibers 307 may pass through an orifice or aperture defined in the probebody and may be affixed to the probe body using epoxy, glue, or thelike.

According to one example, the lens filter 402 may be a long-pass or anotch-pass filter. According to one example, the lens filter 402 isdesigned to decrease a light intensity before the collected light raysimpinge a lens material or other probe materials. Accordingly, the lensfilter 402 allows the optic probe 400 to minimize noise signalgeneration while employing virtually any lens or substrate material.Without inclusion of the lens filter 402, the collected light rays maycreate noise signals such as unwanted peaks, interference, or backgroundfluorescence when impinging the probe components. For example, thecollected light rays may cause probe components to fluoresce whenimpinged. The noise signals, including unwanted peaks, interference, orbackground fluorescence, may be added to or superimposed over spectra ofa desired specimen.

According to one example, the probe design includes a lens filter 402positioned forward or upstream of the lens 404 that decreases orflattens background interference or noise signals attributed tocollected light rays impinging on the lens 404. According to oneexample, minimizing background interference or noise signals attributedto the lens 404 may increase a SNR for the system. Still further,placing the lens filter 402 forward or upstream of other probecomponents may decrease or flatten background interference or noisesignals attributed to collected light rays that impinge downstream probecomponents. According to one example, minimizing background interferenceor noise signals attributed to one or more probe components increases aSNR of the system.

FIG. 5A illustrates Raman spectra of whole milk captured or collectedusing a conventional fiber optic probe without an optical isolator or alens filter, among other features. The various peaks illustrated in theRaman spectra of FIG. 5A correspond to fluorescence and spectral signalscontributed both from the whole milk sample and probe features. FIG. 5Billustrates Raman spectra of whole milk captured or collected with theimproved probes described herein having probe components with aperturesor optical isolators that receive the emission fibers therein. Thevarious peaks illustrated in FIG. 5B correspond to the spectral signalfor the whole milk sample, with minimal fluorescence and spectralsignals contributed by probe features. According to one example, theimproved and conventional probes used to capture the Raman spectraillustrated in FIGS. 5A and 5B are similarly constructed, with probecomponents for each probe made from a same substrate material.Furthermore, the Raman spectra illustrated in FIGS. 5A and 5B areassociated with the same spectrometer, the same parameters, and the samesettings such as laser power, acquisition time, or the like.

A comparison of the Raman spectra illustrated in FIGS. 5A and 5Bdemonstrates how an overall background noise is reduced or flattened forthe improved probe design. With reference to FIG. 5A, the peak 502 apositioned around pixel number 800 in the Raman spectra is generatedfrom the probe components themselves such as the lenses and other probecomponents and is not attributed only to the whole milk sample. Withreference to FIG. 5B, peak 502 b around pixel number 800 is flattenedsince the noise signals attributed to the probe components of FIG. 5Aare essentially eliminated with the improved probe design. A comparisonof the Raman spectra illustrated in FIGS. 5A and 5B demonstrate that thepeak 502 a attributed to the probe components obscured an actual peak502 b of the whole milk sample.

FIG. 7 illustrates an exploded view of a probe tip for a fiber opticprobe 700 having a lens filter, probe components with apertures, opticalisolators, and a multi-ring collection fiber design according to oneexample of the technology. According to one example, the fiber opticprobe 700 may include several components such as a window 101, a lensfilter 102 having an aperture 103, a lens 104 with an aperture 105, acollection fiber filter 106 associated with two or more rings ofcollection fibers 107, the collection fiber filter 106 having anaperture 108, an emission fiber filter 109 associated with one or moreemission fibers 110, and a needle tube 111 that prevents light transferproximate to the probe tip between the emission fibers 110 and thecollection fibers 107. According to one example, a carbon black filledepoxy may be used in place of the needle tube 111. According to oneexample, the components include a distal end located forward or upstreamof the probe and a proximal end located downstream of the probe.According to one example, the distal and proximal ends are provided atcomponent interfaces. According to one example, the distal and proximalends may be positioned substantially perpendicular to the light path.According to one example, the component apertures, the needle tube 111,the carbon black filled epoxy, and the like, are referred to as opticalisolators herein since they may optically isolate the light deliverypath and the light collection path. According to one example, the lensfilter 102, the lens 104, and the collection fiber filter 106 may bedonut-shaped components. According to one example, the emission fiberfilter 109 and the emission fiber 110 may be inserted into or may passthrough corresponding apertures in the donut-shaped components when thefiber optic probe 700 is assembled.

According to one example, the fiber optic probe 700 may include a fiberalignment holder 713 that defines a fiber pattern on an end face 714.For example, FIG. 7 illustrates a centrally positioned emission fiber110 surrounded by a two-ring concentric configuration of collectionfibers 107. FIG. 6B illustrates a concentric two-ring 602,604configuration of optical fibers 107 according to one example. Accordingto one example, the apertures 103,105,108 defined in the fiber opticcomponents may be formed to substantially align with the position of theemission fiber 110 in the fiber alignment holder 713.

According to one example, the multi-ring fiber optic probe 700 enablesdata collection from different measurement depths within a sample orspecimen. For example, the collection fibers 107 associated with theinner ring 602 may collect spectral data from deeper in the specimen. Incontrast, the collection fibers 107 associated with the outer ring 604may collect spectral data from a location closer to the specimensurface. According to one example, the fiber optic probe 700 includes alens 104 that supports different depth measurements. For example, thefiber optic probe 700 may include a lens 104 that directs light rayscaptured from different entry angles into the corresponding collectionfiber rings 602,604, wherein the different entry angles correspond todifferent depth measurements for the sample. According to one example, acomputer system may be electrically coupled to a spectrometer to captureand analyze spectral data associated with the fiber optic probe.According to one example, the computer system may analyze the spectraldata separately for the fiber optic rings 602/604 associated withdifferent measurement depths. For example, the computer system maymanipulate the spectral data using mathematical operations and mayanalyze the spectral data in pre-defined sequences for spectral dataobtained from each fiber ring 602,604. According to one example, thecomputer system may add, subtract, multiply, or perform othermathematical operations on the spectral data associated with the innerand outer rings 602,604.

FIGS. 8A and 8B illustrate cross-sectional views of the fiber opticprobe 700 with light ray traces 812,814 depicting different entry anglesassociated with the collection fiber rings 602,604, respectively. Thefirst collection fiber ring 602 and the second collection fiber ring 604include multiple optical fibers 107. To simplify the ray traceillustration, only one light path is illustrated for each fiber ring602,604. One of ordinary skill in the art will readily appreciate thateach optical fiber 107 associated with the fiber rings 602,604 receivesthe collection light rays substantially simultaneously. According to oneexample, the different entry angles correspond to different depthmeasurements for a sample. With reference to FIG. 8A, the emission fiber110 emits light rays 810 that originate from a laser source and travelthrough the emission fiber filter 109 and the window 101. According toone example, the emitted light rays 810 impinge a sample. According toone example, a portion of the emitted light rays 810 are scattered orreflected back toward the fiber optic probe 700, while a portion causesthe impinged sample to emit a Raman signal. According to one example,the probe 700 receives the reflected light rays and the Raman signal ascollection light rays 812. According to one example, the collectionlight rays 812 impinge the window 101 and are guided through the lensfilter 102, the lens 104, and the collection fiber filter 106 beforebeing directed to the inner ring 602, where the collection light rays812 enter the collection fibers 107 for delivery to a spectrometer.According to one example, the collection light rays 812 impinge thewindow 101 at a first entry angle that corresponds to a first depthmeasurement. According to one example, a thickness of the window 101 maybe selected so that the distal end 815 is positioned at or proximate toa maximum intensity area 816 defined by an intersection of the emissionlight rays and the collection light rays. According to one example, ifthe window 101 is fabricated too thin or too thick, the distal end 815may be situated in areas of reduced intensity such as reduced intensityareas 818, 820. According to one example, placing the distal end 815 ofthe window 101 in an area of reduced intensity is not desirable since itmay reduce an intensity of collected Raman signals.

With reference to FIG. 8B, the emission fiber 110 emits light rays 810that originate from a laser source and travel through the emission fiberfilter 109 and the window 101. According to one example, the emittedlight rays 810 impinge a sample. According to one example, a portion ofthe emitted light rays 810 are scattered or reflected back toward thefiber optic probe 700, while a portion cause the sample to emit a Ramansignal. According to one example, the probe 700 receives the reflectedlight rays and the Raman signal as collection light rays 814. Accordingto one example, the collection light rays 814 impinge the window 101 andare guided through the lens filter 102, the lens 104, and the collectionfiber filter 106 before being directed to the outer ring 604 where thecollection light rays 814 enter the collection fibers 107 for deliveryto a spectrometer. According to one example, the collection light rays814 impinge the window 101 at a second entry angle that corresponds to asecond depth measurement. According to one example, a thickness of thewindow 101 may be selected so that the distal end 815 is positioned ator proximate to a maximum intensity area 816 defined by an intersectionof the emission light rays and the collection light rays. According toone example, if the window 101 is fabricated too thin or too thick, thedistal end 815 may be situated in areas of reduced intensity such asreduced intensity areas 818, 820. According to one example, placing thedistal end 815 of the window 101 in an area of reduced intensity is notdesirable since it may reduce an intensity of collected Raman signals.FIGS. 8A and 8B illustrate separate ray trace diagrams for the two ringcollection fibers in order to simplify the illustration and explanation.One of ordinary skill in the art will readily appreciate that datacollection may occur simultaneously for the multi-rings.

According to one example, the first entry angle associated with thecollection light rays 812 is smaller than the second entry angleassociated with the collection light rays 814. FIG. 8A confirms that thefirst entry angle associated with the collection light rays 812approaches the window 101 closer to a perpendicular angle. Thus, thefirst depth measurement associated with the first entry angle penetratesmore deeply into the sample. FIG. 8B confirms that the second entryangle associated with the collection light rays 814 approaches thewindow 101 closer to a parallel angle. Thus, the second depthmeasurement associated with the second entry angle penetrates shallowerinto the sample.

According to one example, the spectral data received at the fiber opticprobe 700 correspond to different depth measurements and may be used toidentify locations of interest within the sample. For example, the depthmeasurements may be used to identify proximity of the fiber optic probe700 to a surface, a marker, a transition point, or the like.Furthermore, the depth measurements may be used to determine a tissuethickness, a tumor size, a tissue type such as normal, abnormal, muscle,fat, tendon, ligament, or the like. Still further, the depthmeasurements may be used to alert a surgeon when the fiber optic probe700 is near an organ, near a tumor, or approaching a tumor edge or thelike. According to one example, the depth measurements may be used toidentify when the fiber optic probe 700 is approaching a transitionbetween healthy tissue and abnormal tissue such as a tumor, dead tissue,or the like. Accordingly, a surgeon may employ the depth measurements todetermine a tumor boundary or margin before removal.

FIG. 9 illustrates an exploded view of a probe tip for a fiber opticprobe 900 having a lens filter, probe components with apertures, opticalisolators, a multi-ring collection fiber design, and a window blockaccording to one example of the technology. For purposes of efficiencyin reducing an overall number of figures, FIG. 9 illustrates alternativewindow blocks 902 a and 902 b and corresponding windows 904 a, 904 b,respectively, positioned over relevant fiber optic probe components.According to one example, the fiber optic probe 900 may include severalfiber optic probe components such as a window block 902 a or 902 b, awindow 904 a,904 b, a lens filter 102 having an aperture 103, a lens 104with an aperture 105, a collection fiber filter 106 associated with twoor more rings 602,604 of collection fibers 107, the collection fiberfilter 106 having an aperture 108, an emission fiber filter 109associated with one or more emission fibers 110, and a needle tube 111that prevents light transfer proximate to the probe tip between theemission fibers 110 and the collection fibers 107. According to oneexample, a carbon black filled epoxy may be used in place of the needletube 111. According to one example, the components include a distal endlocated forward or upstream of the probe and a proximal end locateddownstream of the probe. According to one example, the distal andproximal ends are provided at component interfaces. According to oneexample, the distal and proximal ends may be positioned substantiallyperpendicular to the light path. According to one example, the componentapertures, the needle tube 311, the carbon black filled epoxy, and thelike, are referred to as optical isolators herein since they mayoptically isolate the light delivery path and the light collection path.FIG. 6B illustrates a concentric two ring 602,604 configuration ofoptical fibers 107 according to one example. According to one example,the lens filter 102, the lens 104, and the collection fiber filter 106may be annular or donut-shaped components. According to one example, theemission fiber filter 109 and the emission fiber 110 may be insertedinto or may pass through corresponding apertures in the donut-shapedcomponents when the fiber optic probe 900 is assembled. According to oneexample, the fiber optic probe 900 may include a fiber alignment holder913 that defines a fiber pattern on an end face 914.

According to one example, the window 904 a,904 b may be formed having aspatial opening at the tip. According to one example, the window 904a,904 b may include a smaller forward-facing window 903 a,903 b thatrestricts a surface area associated with a clear opening of the fiberoptic probe 900. According to one example, the window 904 a may beformed in a truncated cone shape. Alternatively, the window 904 b may beformed in a disc shape with a protruding cylinder. One drawback with thetruncated cone-shaped window 904 a is that a diameter of theforward-facing window 903 a may become enlarged when the window block902 a is polished during manufacture. In contrast, the forward-facingwindow 903 b of the disc-shaped with protrusion window 904 b remainssubstantially equivalent in diameter when the window block 902 b ispolished during manufacture. According to one example, the window 904a,904 b may be constructed of one or more materials such as magnesiumfluoride (MgF₂), fused silica, sapphire, or the like, that aretransparent to light rays over a wide range of wavelengths and avoidspectral interference or noise signals.

According to one example, the window block 902 b placed over thedisc-shaped with protrusion window 904 b may be donut-shaped. Accordingto one example, the window block 902 b may be formed from a lightblocking material such stainless steel, black plastic, or the like, thatis coupled to the disc-shape with protrusion window 904 b. According toone example, the window block 902 b may be coupled to the disc-shapedwith protrusion window 904 b using an epoxy such as a light absorbingepoxy including a carbon black-loaded epoxy. According to anotherexample, the disc-shaped with protrusion window 904 b may be coated witha carbon black filled epoxy. In this case, the window block 902 b may beomitted. According to another example, the disc-shaped with protrusionwindow 904 b may be coated with an epoxy to reduce or minimize any strayor unwanted light from entering the probe tip, which reduces a chancethe stray or unwanted light will enter the collection fibers 107.

FIGS. 10A and 10B illustrate cross-sectional views of the fiber opticprobe 900 having the disc-shaped with protrusion window 904 b and lightray traces 1012,1014 depicting different entry angles associated withthe collection fiber rings 602,604, respectively. To simplify the raytrace illustration, only one light path is illustrated for each fiberring 602,604. One of ordinary skill in the art will readily appreciatethat each optical fiber 107 associated with the fiber rings 602,604receives the collection light rays substantially simultaneously. Withreference to FIG. 10A, the emission fiber 110 emits light rays 1010 thatoriginate from a laser source and travel through the emission fiberfilter 109 and the window 904 b. According to one example, the emittedlight rays 1010 impinge a sample. According to one example, a portion ofthe emitted light rays 1010 are scattered or reflected back toward thefiber optic probe 900, while a portion cause the impinged sample to emita Raman signal. According to one example, the probe 900 receives thereflected light rays and the Raman signal as collection light rays 1012.According to one example, the collection light rays 1012 impinge thewindow 904 b and are guided through the lens filter 102, the lens 104,and the collection fiber filter 106 before being directed to the innerring 602, where the collection light rays 1012 enter the collectionfibers 107 for delivery to a spectrometer. According to one example, thecollection light rays 1012 impinge the window 904 b at a first entryangle that corresponds to a first depth measurement. According to oneexample, a thickness of the window 904 a,904 b may be selected so thatthe distal end 1015 is positioned at or proximate to a maximum intensityarea 1016 defined by an intersection of the emission light rays and thecollection light rays. According to one example, if the window 904 a,904b is fabricated too thin or too thick, the distal end 1015 may besituated in areas of reduced intensity such as reduced intensity areas1018, 1020. According to one example, placing the distal end 1015 of thewindow 904 a,904 b in an area of reduced intensity is not desirablesince it may reduce an intensity of collected Raman signals.

With reference to FIG. 10B, the emission fiber 110 emits light rays 1010that originate from a laser source and travel through the emission fiberfilter 109 and the window 904 b. According to one example, the emittedlight rays 1010 impinge a sample. According to one example, a portion ofthe emitted light rays 1010 are scattered or reflected back toward thefiber optic probe 900, while a portion cause the sample to emit a Ramansignal. According to one example, the probe 900 receives the reflectedlight rays and the Raman signal as collection light rays 1014. Accordingto one example, the collection light rays 1014 impinge the window 904 band are guided through the lens filter 102, the lens 104, and thecollection fiber filter 106 before being directed to the outer ring 604where the collection light rays 1014 enter the collection fibers 107 fordelivery to a spectrometer. According to one example, the collectionlight rays 1014 impinge the window 904 b at a second entry angle thatcorresponds to a second depth measurement. According to one example, athickness of the window 904 a,904 b may be selected so that the distalend 1015 is positioned at or proximate to a maximum intensity area 1016defined by an intersection of the emission light rays and the collectionlight rays. According to one example, if the window 904 a,904 b isfabricated too thin or too thick, the distal end 1015 may be situated inareas of reduced intensity such as reduced intensity areas 1018, 1020.According to one example, placing the distal end 1015 of the window 904a,904 b in an area of reduced intensity is not desirable since it mayreduce an intensity of collected Raman signals.

According to one example, the first entry angle associated with thecollection light rays 1012 is smaller than the second entry angleassociated with the collection light rays 1014. FIG. 10A confirms thatthe first entry angle associated with the collection light rays 1012approaches the smaller forward-facing window 903 b closer to aperpendicular angle. Thus, the first depth measurement associated withthe first entry angle penetrates more deeply into the sample. FIG. 10Bconfirms that the second entry angle associated with the collectionlight rays 1014 approaches the smaller forward-facing window 903 bcloser to a parallel angle. Thus, the second depth measurementassociated with the second entry angle penetrates shallower into thesample.

FIG. 11 illustrates an exploded view of a probe tip for a fiber opticprobe 1100 having a lens filter, probe components with apertures,optical isolators, a multi-ring collection fiber design, and a lightblock component according to one example of the technology. According toone example, the fiber optic probe 1100 may include several fiber opticprobe components such as a window 101, a lens filter 102 having anaperture 103, a light blocking component 1102, a lens 1104 with anaperture 1105, a collection fiber filter 106 associated with two or morerings 602,604 of collection fibers 107, the collection fiber filter 106having an aperture 108, an emission fiber filter 109 associated with oneor more emission fibers 110, and a needle tube 111 that prevents lighttransfer proximate to the probe tip between the emission fibers 110 andthe collection fibers 107. According to one example, a carbon blackfilled epoxy may be used in place of the needle tube 111. According toone example, the components include a distal end located forward orupstream of the probe and a proximal end located downstream of theprobe. According to one example, the distal and proximal ends areprovided at component interfaces. According to one example, the distaland proximal ends may be positioned substantially perpendicular to thelight path. According to one example, the component apertures, theneedle tube 111, the carbon black filled epoxy, and the like, arereferred to as optical isolators herein since they may optically isolatethe light delivery path and the light collection path. FIG. 6Billustrates a concentric two ring 602,604 configuration of opticalfibers 107 according to one example. According to one example, the lensfilter 102 and the collection fiber filter 106 may be annular ordonut-shaped components. According to one example, the lens 1104 mayinclude a parabolic or truncated cone-shape designed for total internalreflection. According to one example, the lens 1104 may include anaperture 1105 formed therethrough. According to one example, theemission fiber filter 109 and the emission fiber 110 may be insertedinto or may pass through corresponding apertures in the probe componentswhen the fiber optic probe 1100 is assembled.

According to one example, the lens 1104 may be formed as a singlecomponent lens. For example, the lens 1104 may be formed as a singlecomponent lens having a truncated cone shape. Alternatively, the lens1104 may be formed as a multi-component lens. According to one example,the lens 1104 may include an inner portion formed from a material thatis transparent to light rays over a wide range of wavelengths and anouter portion having a lower refractive index. In other words, the lens1104 may be constructed to form a waveguide. For example, the innerportion of the lens 1104 may be formed from sapphire and the outerportion of the lens 1104 may be formed from an ultra-violet (UV) curedepoxy, a two-component epoxy, Teflon® amorphous fluoropolymer (AF)resins, or the like. According to one example, the outer portion of thelens 1104 may have a low refractive index material that is deposited onthe surface by evaporation, sputtering, or other deposition techniques.According to another example, the entire lens 1104 may be formed from atransparent material as long as the material does not interfere with thespectroscopic measurement. For example, transparent or low indexmaterials may include MgF₂, fused silica, sapphire, calcium fluoride(CaF₂), barium fluoride (BaF₂), clear polymers, or the like. Accordingto one example, air may be used as a low index material if steps aretaken to ensure the air gap is maintained. According to one example,materials other than MgF₂ may allow additional low index coveringmaterials to achieve total internal reflectance (TIR). With respect toclear polymers, these may include fluoropolymers, chlorofluoro polymers,acrylic, polycarbonate, or the like.

According to one example, a shape of the lens 1104 may be selected toachieve a desired depth measurement for the sample. For example, a shapeof the parabola or an angle of the cone surface may be selected toachieve a desired depth measurement for the sample. In other words, theshape of the lens 1104 determines entry angles for the collected lightrays received from the sample. Furthermore, the size of the aperture1105 may determine a size of the interrogation spot impinged by theexcitation laser light. According to one example, a larger interrogationspot may provide more excitation laser light and a smaller interrogationspot may provide less excitation laser light. Still further, the window101 placed over the probe components may be designed to further definethe spatial measurement area. For example, a smaller diameter window 101may restrict entry of collected laser light or Raman signal while alarger diameter window 101 may allow entry of more collected laser lightor Raman signal. According to one example, the window 101 may be used tomaximize overlap or to protect the probe elements.

FIG. 12 illustrates a cross-sectional view of the fiber optic probe 1100having the TIR truncated cone-shaped lens 1104 and light ray trace 1212depicting an entry angle associated with the collection fiber rings602,604, respectively. To simplify the ray trace illustration, only onelight path is illustrated for fiber ring 604. One of ordinary skill inthe art will readily appreciate that each optical fiber 107 associatedwith the fiber rings 602,604 receives the collection light rayssubstantially simultaneously. According to one example, the differententry angles correspond to different depth measurements for a sample.The emission fiber 110 emits light rays 1210 that originate from a lasersource and travel through the emission fiber filter 109 and the window101. According to one example, the emitted light rays 1210 impinge asample.

According to one example, a portion of the emitted light rays 1210 arescattered or reflected back toward the fiber optic probe 1100, while aportion causes the impinged sample to emit a Raman signal. According toone example, the probe 1100 receives the reflected light rays and theRaman signal as collection light rays 1212. According to one example,the collection light rays 1212 impinge the window 101 and are guidedthrough the lens filter 102, the lens 1104, and the collection fiberfilter 106 before being directed to the outer ring 602, where thecollection light rays 1212 enter the collection fibers 107 for deliveryto a spectrometer. According to one example, the collection light rays1212 impinge the window 101 at a first entry angle that corresponds to afirst depth measurement. According to one example, a thickness of thewindow 101 may be selected so that the distal end 1215 is positioned ator proximate to a maximum intensity area 1216 defined by an intersectionof the emission light rays and the collection light rays. According toone example, if the window 101 is fabricated too thin or too thick, thedistal end 1215 may be situated in areas of reduced intensity such asreduced intensity areas 1218, 1220. According to one example, placingthe distal end 1215 of the window 101 in an area of reduced intensity isnot desirable since it may reduce an intensity of collected Ramansignals.

While not shown, a portion of the collection light rays are alsodirected to the collection fibers 107 corresponding to the inner ring602 for delivery to a spectrometer. One of ordinary skill in the artwill readily appreciate that the TIR lens may be constructed of variousshapes, dimensions, or the like, to allow different depth measurements.Furthermore, the TIR lens may include different surface angles thatallow different depth measurements.

According to one example, the lens components 104,204,304,404 describedthroughout this disclosure may include any desired configuration thatmanipulates light rays passing therethrough. According to one example,the lens components 104,204,304,404 may include a single piececonstruction. Alternatively, the lens components 104,204,304,404 mayinclude a multi-piece construction. The technology further providesnovel and non-obvious lens components having facets. With reference toFIG. 13, the lens 1300 includes an aperture 1301 and an active facet1302 having a flat surface oriented at a desired angle to form arefractive, reflective, or total internally reflective structure, amongother structures. With reference to FIG. 14, the lens 1400 includes anaperture 1401 and facets 1402 a,1402 b having curved surfaces that formrefractive, reflective, or total internally reflective structures, amongother structures. According to one example, the lens may include facetshaving a combination of curved and flat surfaces oriented at desiredangles to form refractive, reflective, or total internally reflectivestructures, among other structures. According to one example, the lensmay include three refractive rings, which may correlate to the emissionfibers 110 and a two-ring pattern of the collection fibers 107, asillustrated in FIG. 6B.

According to one example, the lens may include facets having flatsurfaces that allow light rays to pass therethrough substantiallyunaltered. For example, the flat surface may be oriented substantiallyperpendicular to a light path that enters the lens. According to oneexample, the lens may include facets with a viewing path that isunobstructed by the lens refractive/reflective surfaces. According toone example, the fiber optic probes described herein may include animaging bundle or camera positioned proximate to the facets having theunobstructed viewing path. According to one example, the unobstructedviewing path may be formed at a center of the lens, among otherlocations. The unobstructed viewing path may be beneficial for fiberoptic probes that combine spectroscopy with camera images, imagingbundles, optical coherence tomography (OCT) fibers, or the like.

According to one example, a facet configuration may be selected toseparately achieve desired illumination depths and collectionefficiencies. According to one example, the facet configurations may beselected to adjust a height, width, thickness, and shape of a refractiveor reflective feature in order to maximize fiber optic probeperformance. According to one example, the facet configurations may beadjusted to control light ray entry or exit angles. In contrast,conventional spherical or aspheric lenses offer less control over lightray entry or exit angles. According to one example, the lens may beconfigured to set an opening size at a specific value to provide adesired interrogation spot, region, depth, or the like. According to oneexample, the lens may include separate lenses that perform depthmeasurements. According to one example, the fiber optic probes mayinclude a depth measuring lens positioned at a peripheral location.

According to one example, the lens may include a facet having arefractive, reflective, or total internally reflective angle thatcaptures collection light from an angle that is outward and away fromthe emission light rays. According to one example, this configurationenables sub-surface or depth measurements. According to one example, thedepth measurements obtained from the fiber optic probes may besubstantially equivalent to depth measurements obtained from spatiallyoffset Raman spectroscopy (SORS). According to one example, a detectormay be provided to receive refracted, scattered, or reflected lightsignals from the collection fibers 107, along with a correspondingcollection position. According to one example, the collection positionmay be associated with a quadrant position or the like. According to oneexample, the system may employ spectral position information obtainedfrom the individual fibers 107 to determine a direction from which thecollection light was received. According to one example, the spectralposition information may be used to determine a direction the fiberoptic probe may be moved to gather additional relevant spectra.

According to another example, the fiber optic probe may be configured tooffset an angle of the emission light rays in an outward direction andmay include collection fibers 107 located proximate the emission fiber110 to capture the collected light rays. According to one example, asurface probe may be inserted into the aperture of the lens to obtaincollected light rays. According to one example, the emission fiber 110may be employed to obtain both refracted and scattered or reflectedlight rays. According to yet another example, the fiber optic probe mayinclude a separate lens associated with each fiber or fiber group.

According to one example, the lens may include facets positioned andoriented to maximize the performance of the fiber optic probe forparticular applications. For example, the lens may include a pluralityof facets oriented at selected angles and positions relative to opticalfibers, light rays, and other facets to maximize performance of thefiber optic probe for particular applications. According to one example,custom lens designs allow optical fibers to be positioned closer torefractive or reflective surfaces. In contrast, conventional sphericallens designs may introduce losses due to vignetting, which is areduction of image brightness or saturation proximate to a lensperiphery as compared to a center of the lens image. According to oneexample, a lens having a plurality of facets may provide a fiber opticprobe with a short focal length. Generally, conventional lenses performpoorly with fiber optic probes having a high number of optical fibersassociated with an increased probe diameter because the lens diametermust be increased accordingly to accommodate the high number of opticalfibers, which causes a low numerical aperture associated with low lightcollection.

According to one example, a plurality of facets may be oriented relativeto an optical fiber arrangement associated with the fiber optic probe.For example, the plurality of facets may be oriented to accommodate aring pattern arrangement of optical fibers 107. According to anotherexample, the plurality of facets may be oriented relative to light rayentry or exit angles associated with the fiber optic probe. According toyet another example, the plurality of facets may be oriented relative toadjacent facets within the fiber optic probe. According to anotherexample, the plurality of facets may be static such that the facetorientation is unchanged after manufacture. One of ordinary skill in theart will readily appreciate that a plurality of facets may be orientedto accommodate any pattern of optical fibers provided in the fiber opticprobe, any light ray entry or exit angles associated with the fiberoptic probe, or any arrangements of other facets in the fiber opticprobe.

According to one example, the lens with facets may be placed ordeposited over the collection fiber filter 106, the emission fiberfilter 109, the collection fibers 107, or the emission fiber 110. Forexample, the lens with facets may be placed or deposited directly on topof the collection fiber filter 106, the emission fiber filter 109, thecollection fibers 107, or the emission fiber 110. According to anotherexample, the lens with facets may be formed of a multi-piece design suchthat separate lens portions may be placed or deposited over thecollection fiber filter 106, the emissions fiber filter 109, thecollection fibers 107, or the emission fiber 110. According to oneexample, the collection fiber filter 106 and the emissions fiber filter109 may be placed over the collection fibers 107 and the emission fiber110, respectively. According to another example, different filters maybe placed over individual or multiple optical fibers. According to oneexample, providing different filters over individual or multiple opticalfibers renders a fiber optic probe capable of performing multiplespectroscopic techniques. According to one example, a same fiber opticprobe may perform multiple emissions wavelength Raman or otherspectroscopy, including utilizing time gated Raman.

According to one example, the lens with facets offers several advantagesover conventional lenses. For example, the facets offer control overcustom lens designs. Furthermore, the facets enable the design andfabrication of thin and light weight lenses, among providing otherbenefits.

FIG. 13 illustrates the lens 1300 having an aperture 1301 and an activefacet 1302 having an angled surface or a truncated cone-shaped centralportion that defines a perimeter of the aperture 1301. With reference toFIGS. 1 and 13, the lens 1300 functions substantially equivalent to thelens 104 and may replace it. According to one example, the aperture 1301allows the emission light rays to pass through the lens 1300substantially unaltered. According to one example, one or more of theemission fibers 110, the needle tube 111, a collimating lens, or theemission fiber filter 109 may be configured to align or pass through theaperture 1301. According to one example, a portion of the emission lightrays are scattered or reflected back toward the fiber optic probe 100,while a portion causes the impinged sample to emit a Raman signal.According to one example, the probe 100 receives the reflected lightrays and the Raman signal as collection light rays. According to oneexample, the collection light rays impinge the window 101 and are guidedthrough the lens filter 102 to the lens 1300 where they impinge upon theactive facet 1302 before being directed toward the collection fibers 107for delivery to the spectrometer. With reference to FIG. 6A, theposition and surface angle for the active facet 1302 are selected tocorrespond to the single ring 701 configuration defined by thecollection fibers 107. According to one example, the position andsurface angle for the active facet 1302 may be selected to achieve adesired depth measurement. According to one example, the facet 1302 isan angled refractive surface. The remaining facets depicted in the lens1300 are non-active facets that do not contribute light rays to thecollection fiber arrangements. According to one example, the fiber opticprobe 100 may include a single piece or multi-piece lens 1300.

According to another example, the lens 1300 may include a singlerefractive or reflective step that is curled in spiral pattern (notshown), instead of employing discrete annular rings. According to yetanother example, the facets may be arranged in a partial ring. Forexample, the facets may be arranged in a partial ring that correspondsto one or more quadrants. Still further, the facets may be arranged tocorrespond to individual fibers. According to one example, the lens 1300may utilize reflective facets that provide total internal reflection.According to another example, the lens 1300 may utilize reflectivefacets, with or without refractive facets.

With respect to filters, a laser blocking filter may be disposed forwardor upstream of the collection fibers to prevent undesired light raysfrom entering the collection fibers. According to one example, thecollection fiber filter 106 associated with the collection fibers 107may include a laser blocking filter. Furthermore, a laser blockingfilter may be used at the delivery end of an optical fiber to removesilica Raman bands contributed by an optical fiber itself before itilluminates a sample. According to one example, the emission fiberfilter 109 associated with the emission fibers 110 may include a lasercleanup filter. According to one example, the collection fiber filter106 and the emission fiber filter 109 may be designed to match theconfiguration of the corresponding collection fibers 107 and emissionfibers 110.

According to one example, the fiber optic probes may include acollimating lens associated with the emission fibers 110. According toone example, the collimating lens may include a GRIN (gradient index) orother collimating lens. According to another example, the GRIN lens maybe eliminated. According to one example, the collimating lens may bemounted on the needle tube 111 to prevent light transfer proximate tothe probe tip between the emission fibers 110 and the collection fibers107. According to one example, the needle tube 111 may surround orencapsulate the emission fibers 110 and the emission fiber filter 109and may extend to the proximal face of the window 101 in order tooptically isolate the emission fibers 110 and the collection fibers 107.

According to one example, the lenses may be fabricated using massproduction techniques. For example, the lens may be fabricated usingUV/2 photon cured resins such as Nanoscribe or other polymers utilizingtechniques like photolithography, UV cured polymer stamping, thermalimprinting, injection molding or other molding technique,stereolithographic printing, other 3D printing techniques, or the like.According to another example, the lens may be fabricated using moldedglass that enables lens manufacturing with higher refractive indexglasses. According to yet another example, the lens may be fabricatedusing sol gel or single point diamond turning, among other polishingtechniques.

According to one example, the fiber optic probe may include a separatelens for each fiber or fiber group. According to one example, the lensmay include a complex shape with multiple facets defining a centralportion having multiple refractive and reflective surfaces. According toone example, the central portion allows light rays to pass through thelens unobstructed. According to one example, one or more of the emissionfibers 110 and the emission filter 109 may be configured to align withthe center portion having active facets that angle the light rays towardthe collection fibers 107. According to one example, the active facetsmay employ reflection or refraction to guide light rays to acorresponding one of the two rings 602,604 of collection fibers 107.According to one example, the facets may represent reflective orrefractive rings that match up with the two-ring geometry 602,604 of thecollection fibers 107. According to one example, the fiber optic probemay include a single piece or multi-piece lens having facets thatmeasure surface features.

FIG. 14 illustrates a lens 1400 having an aperture 1401 and two activefacets 1402 a,1402 b having angled surfaces. With reference to FIGS. 7and 14, the lens 1400 functions substantially equivalent to the lens 104and may replace it. According to one example, the aperture 1401 allowsthe emission light rays to pass through the lens 1400 substantiallyunaltered. According to one example, the aperture 1401 may align withthe emission optical fibers 110. According to one example, one or moreof the emission fibers 110, the needle tube 111, a collimating lens, orthe emission fiber filter 109 may be configured to align or pass throughthe aperture 1401. According to one example, the needle tube 111 may beomitted and replaced with a carbon black filled epoxy. According to oneexample, the collected light rays that reflect off or are emitted fromthe sample are guided to the lens 1400 where they impinge upon theactive facets 1402 a,1402 b before being directed toward the collectionfibers 107 for delivery to the spectrometer. With reference to FIG. 6B,the positions and surface angles for the active facets 1402 a,1402 b areselected to correspond to the two ring 602,604 configuration defined bythe collection fibers 107. According to one example, the positions andsurface angles for the active facets 1402 a,1402 b may be selected toachieve desired depth measurements.

According to one example, the facets 1402 a,1402 b are angled refractivesurfaces. The remaining facets depicted in the lens 1400 are non-activefacets that do not contribute light rays to the collection fiberarrangements. According to one example, the facet 1402 a is an angledrefractive surface that is aligned with an outer ring 604 of collectionoptical fibers 107. According to one example, facet 1402 b is an angledrefractive surface that is aligned with an inner ring 602 of collectionoptical fibers 107.

According to another example, the lens 1400 may include a singlerefractive or reflective step that is curled in spiral pattern (notshown), instead of employing discrete annular rings. According to yetanother example, the facets may be arranged in a partial ring. Forexample, the facets may be arranged in a partial ring that correspondsto one or more quadrants. Still further, the facets may be arranged tocorrespond to individual fibers. According to one example, the lens mayutilize reflective facets that provide total internal reflection.According to another example, the lens may utilize reflective facets,with or without refractive facets.

As discussed above, employing facets enables the design and fabricationof thin and light weight lenses. This concept is demonstrated withreference to FIGS. 14 and 15. FIG. 14 illustrates a lens 1400 havingfacets 1402 a,1402 b with a continuously angled surface. FIG. 15illustrates that a substantially equivalent facet may be constructedfrom two or more thinner concentric facets having similarly angledrefractive surfaces. Specifically, FIG. 15 illustrates a lens 1500having two concentric facets 1502 a,1502 b with similarly angledrefractive surfaces. According to one example, each concentric facet1502 a,1502 b is substantially half the depth or thickness of thecorresponding facet 1402 a illustrated in FIG. 14. Stated differently,the thickness dimension of the concentric facets 1502 a,1502 b issubstantially equivalent to slicing the facet 1402 a in a vertical ordepth direction at approximately half the depth of the lens 1400. FIG.15 illustrates that the concentric facets 1502 a,1502 b may be nestedsuch that the facet 1502 a includes a small sized diameter and the facet1502 b includes larger sized diameter. According to this example, thenesting arrangement allows formation of a lens 1500 having half thedepth of lens 1400, with substantially equivalent performance. Since thetwo concentric facets 1502 a,1502 b have a substantially equivalentsurface area as to facet 1402 a, the lens 1500 with concentric facets1502 a,1502 b having a reduced thickness, will perform substantiallysimilar to lens 1400 having facet 1402 a.

According to another example, FIG. 16 illustrates a lens 1600 thatincludes four concentric facets 1602 a-1602 d with similarly angledrefractive surfaces. According to one example, each concentric facet1602 a-1602 d includes substantially a quarter the depth of the facet1402 a illustrated in FIG. 14. Stated differently, the thicknessdimension of the concentric facets 1602 a-1602 d is substantiallyequivalent to slicing the facet 1402 a in a vertical or depth directionat approximately a quarter the depth of the lens 1400. FIG. 16illustrates that the concentric facets 1602 a-1602 d may be nested suchthat facet 1602 a includes a small sized diameter and facet 1602 dincludes the largest sized diameter. According to this example, thenesting arrangement enables the lens 1600 to have a quarter the depth ofthe lens 1400, with substantially equivalent performance. Since the fourconcentric facets 1602 a-1602 d have a substantially similar surfacearea as compared to the facet 1400, the lens 1600 with concentric facets1602 a-1602 d, having a reduced thickness, will perform substantiallysimilar to lens 1300 having facet 1302 a. According to one example, athinner lens design enables the fabrication of short, rigid probe tipsthat may be used with flexible endoscopes or the like.

FIG. 17A illustrates a bottom view of a lens component 1700A made from aclear optical substrate 1701 having individual lenslets 1702 a-1702 gwith facets. According to one example, the lenslets 1702 a-1702 g maycollimate light rays emitted from individual fibers. According to oneexample, the lens 1700A may include an array of individual lenslets 1702a-1702 f that correspond to individual collection fibers 107 providedthereunder. According to one example, lenslet 1702 g may correspond toan emission fiber 110. According to one example, the lenslet 1702 g maybe omitted, leaving an aperture in its place. According to one example,the lens 1700A may be employed for a fiber optic probe having individualcollection fibers 107 arranged around the emission fiber 110. Accordingto one example, the lens 1700A may be employed for a fiber optic probehaving two lenses, with one lens corresponding to the emission fiber 110and a second lens corresponding to a bundle of the collection fibers 107or a single collection fiber 107. According to one example, a lens shapemay be selected to focus an image at a common point. According to oneexample, the lens 1700A may include an alignment mechanism 1704 thatproperly orients the individual lenslets 1702 a-1702 f withcorresponding collection fibers 107. For example, the probe may includea fiber alignment holder 113 with an end face 114 having a hole thatreceives a post 1704 provided at the lens component.

FIG. 17B illustrates a side profile of the lens component 1700 showingthe post 1704 protruding therefrom. According to one example, the lens1700B may include a hemisphere lens 1705 and individual lenslets 1702a-1702 g that correspond to individual fibers or bundle of fibers.According to one example, the hemisphere lens 1705 may be common to alllenslets 1702 a-1702 g. According to one example, the lens 1700B mayenable separate lens designs for individual fibers or bundle of fibers.For example, the separate lens designs may enable custom features foreach lens such as specific wavelength filters, or the like, for eachfiber or bundle of fibers. According to one example, providing customfeatures for each lens enhances multi-spectroscopy probe performance,Raman spectroscopy with imaging such as coherent fiber bundle or camera,OCT, Fluorescence, diffuse reflectance, or the like. According to oneexample, the individual lenses 1702 a-1702 g may include non-facetedfeatures.

FIG. 18 illustrates an exploded view of a probe tip for a fiber opticprobe 1800 having a built-in calibration sample according to one exampleof the technology. According to one example, the fiber optic probe 1800may include several components such as a window 101, a lens filter 102having an aperture 103, a lens 104 with an aperture 105, a collectionfiber filter 106 associated with one or more collection fibers 107, thecollection fiber filter 106 having an aperture 108, an emission fiberfilter 109 associated with one or more emission fibers 110, acalibration sample 1802, a calibration filter 1804, a calibration fiber1806, and a needle tube 111 that prevents light transfer proximate tothe probe tip between the emission fibers 110 and the collection fibers107. According to one example, a carbon black filled epoxy may be usedin place of the needle tube 111. According to one example, thecomponents include a distal end located forward or upstream of the probeand a proximal end located downstream of the probe. According to oneexample, the distal and proximal ends form component interfaces.According to one example, the distal and proximal ends may be positionedsubstantially perpendicular to the light path. According to one example,the lens filter 102, the lens 104, and the collection fiber filter 106may be donut-shaped components. According to one example, the emissionfiber filter 109 and the emission fiber 110 may be inserted into or maypass through corresponding apertures in the donut-shaped components whenthe fiber optic probe 1800 is assembled.

According to one example, the fiber optic probe 1800 includes severalcollection fibers 107 such that one or more collection fibers may bereserved as a calibration fibers 1806. According to one example, acalibration filter 1804 may be placed in between the calibration fiber1806 and a calibration sample 1802. According to one example, thecalibration sample 1802 may include Tylenol®, NIST glass, or the like.

Prior to this technology, probe or spectrometer calibration wasperformed using an external calibration sample or an externalcalibration light source. External calibration has drawbacks in medicalapplications that require sterile environments. According to oneexample, the fiber optic probe 1800 eliminates drawbacks associated withperforming calibration external of the probe tip. According to oneexample, the calibration fiber 1806 may be configured to originate acalibration light internal to the probe tip. According to one example,performing internal calibration simplifies, expedites, and eliminatessources of non-uniformity as compared to performing external calibrationof samples or sources. Furthermore, an internal calibration source maybe safely employed in medical settings that require a sterileenvironment. According to one example, the internal calibration fiber1806 offers a sealed or sterilized calibration source that is requiredin medical settings. According to one example, the calibration sample1802 may be cut or shaped for placement at a fiber distal end.

According to one example, the fiber optic probe 1800 may employ thecalibration fibers 1806 to deliver laser light used for Ramanexcitation. According to one example, the calibration laser light may beobtained from a laser splitter and may impinge or interact with aninternal calibration sample 1802. According to one example, employingthe laser splitter allows a same laser light source to be used both formeasurement and calibration. According to one example, a reflectivematerial such as an aluminum mirror may be placed proximate to the probetip to increase an intensity of the calibration spectra.

FIG. 19 illustrates an alternative calibration system 1900 that includesa spectrometer 1901 optically coupled to a calibration module 1902 and afiber optic probe 1904 according to one example of the technology. Thefiber optic probe 1904 may include, for example, the fiber optic probesdescribed herein. According to one example, a coupler 1905 may beprovided to optically couple the calibration module 1902 and the fiberoptic probe 1904. According to one example, an excitation laser source1906 generates an excitation laser light that is directed to a splitteror diverter 1907. According to one example, the splitter 1907 may splitthe excitation laser light according to a 50/50 ratio, a 60/40 ratio, orthe like. According to one example, the splitter 1907 may be opticallycoupled to a calibration emission fiber 1908 associated with thecalibration module 1902 and a probe emission fiber 1909 associated withthe fiber optic probe 1904. According to one example, the excitationlaser light may impinge upon the calibration sample 1910 causing it toemit a calibration signal that is captured by a calibration collectionfiber 1911 and provided to a probe collection fiber 1912 through thecoupler 1905. According to one example, the calibration system 1900 mayinclude multiple calibration samples and may be configured to selectamong the plurality of calibration samples. According to one example,the calibration system 1900 may include a rotary wheel that rotates toprovide a desired calibration sample. Alternatively, the calibrationsystem 1900 may include additional calibration modules assigned toadditional calibration samples. In this case, the calibration system1900 may include additional splitters 1907 and couplers 1905 to supportthe additional calibration modules.

According to one example, the probe collection fiber 1912 may direct thecalibration signal into the fiber optic probe 1904 where the remainingprobe collection fibers 1914 receive the calibration signal and directit into the spectrometer 1901. According to one example, the calibrationsystem 1900 provides a calibration signal that is employed in medicalsettings. Employing a separate calibration module 1902 offers anadvantage that the calibration sample 1910 may be changed to a differentcalibration sample if needed. A further advantage of using a separatecalibration module 1902 may be that the calibration sample 1910 is notrequired to be built into a fiber optic probe itself.

According to another example, a calibrated white light source or anatomic line source may be injected into a proximal end of thecalibration fiber 1806 for the fiber optic probe 1800 or the probeinjection fiber 1912 for the fiber optic probe 1904. According to oneexample, a known response of the white light or the atomic line sourcemay be used for calibration purposes.

The technology provides a method for constructing a smallest diameterconcentric multi-ring fiber optic bundle with the largest number ofcollection optical fibers. FIG. 20 illustrates one example of aconcentric, two (2) ring 602,604 fiber optic bundle that provides thelargest number of collection optical fibers. In a first operation, afirst or inner ring 602 may include several 300-micron core opticalfibers 107 placed around a 0.021″ outer diameter (OD)polytetrafluoroethylene (PTFE) Teflon-coated pin or wire 2002. In asecond operation, heat shrink tubing may be employed to securely holdthe first ring 602 of optical fibers 107 tightly against the outerdiameter of the pin 2002. In a third operation, the optical fibers 107may be secured together using a thin epoxy that fixedly holds the firstring 602 of optical fibers in position when cured. In a fourthoperation, after the epoxy is cured, the heat shrink may be removed andthe second ring 604 of 300-micron core fibers 107 may be placed aroundthe inner ring 602 of fibers. In a fifth operation, a heat shrink tubingmay be employed to securely hold the optical fibers 107 tightly againstthe first ring 602 of optical fibers 107. In a sixth operation, theoptical fibers 107 may be secured together using a thin epoxy thatfixedly holds the second ring 604 of optical fibers 107 in position whencured. In a seventh operation, the PTFE pin 2002 is removed from thefirst and second rings 602,604 of optical fibers 107. The removed PTFEpin 2002 leaves behind an aperture or hole that receives an emissionoptical fiber 110 therethrough. In an eighth operation, the opticalfibers 107 that form the first and second rings 602,604 may be polishedto an optical quality finish. In a separate operation, the emissionfiber 110 may be polished and inserted into the hole at the centerbundle of first and second rings 602,604. In another operation, thefiber collection filter 106 may be placed on the first and second rings602,604 of polished optical fibers 107 and secured with clear opticalepoxy.

It is to be understood that while a certain form of the technology isillustrated, it is not to be limited to the specific form or arrangementherein described and illustrated. It will be apparent to those skilledin the art that various changes may be made without departing from thescope of the invention and the invention is not to be considered limitedto what is shown and described in the specification and any drawings orfigures included herein.

According to one example, the descriptions provided herein may be usedfor any optical probe. Additionally, while the examples provided hereinare directed to the medical field, one of ordinary skill in the art willreadily appreciate that this technology may be used with any fields orapplications that employ chemical analysis. Examples are described abovewith the aid of functional building blocks that illustrate theimplementation of specified operations and relationships thereof. Theboundaries of these functional building blocks have been arbitrarilydefined herein for the convenience of the description. Alternateboundaries can be defined so long as the specified functions andrelationships thereof are appropriately performed. While the foregoingillustrates and describes examples of this technology, it is to beunderstood that the technology is not limited to the constructionsdisclosed herein. The technology may be embodied in other specific formswithout departing from its spirit. Accordingly, the appended claims arenot limited by specific examples described herein.

What is claimed is:
 1. A fiber optic probe having a distal sampling end,a proximal end, a light delivery path therethrough, and a lightcollection path therethrough, the fiber optic probe comprising: a windowdisposed at the distal sampling end of the fiber optic probe, the windowhaving a distal end and a proximal end; a lens disposed near theproximal end of the window, the lens having a distal end, a proximalend, and an aperture; a light delivery optical fiber having a distal endand a proximal end, the distal end being received by the lens aperture;an optical isolator provided within the lens aperture to opticallyisolate the light delivery path and the light collection path; and acollection optical fiber in optical communication with the lens andwindow.
 2. The fiber optic probe according to claim 1, furthercomprising a lens collection filter disposed between the window and thelens, the lens collection filter having a distal end, a proximal end,and an aperture.
 3. The fiber optic probe according to claim 1, whereinthe lens is at least one of refractive, reflective, or totallyinternally reflective.
 4. The fiber optic probe according to claim 1,wherein the collection optical fiber is provided in a multi-ringarrangement.
 5. The fiber optic probe according to claim 1, furthercomprising a fiber collection filter disposed between the lens and thecollection optical fiber, the fiber collection filter having a distalend, a proximal end, and an aperture.
 6. The fiber optic probe accordingto claim 1, further comprising an emission filter disposed at a distalend of the light delivery optical fiber.
 7. The fiber optic probeaccording to claim 1, wherein the light delivery optical fiber emitslaser light at or forward of the distal end of the lens.
 8. The fiberoptic probe according to claim 2, wherein the optical isolator includesa light blocking coating provided along a circumference of at least oneof the lens collection filter aperture and the lens aperture.
 9. Thefiber optic probe according to claim 1, further comprising a windowblock provided at the distal end of the window, wherein the window blockrestricts a surface area of the window.
 10. The fiber optic probeaccording to claim 1, further comprising a core tube that is frictionfitted into the alignment feature aperture.
 11. A fiber optic probehaving a distal sampling end, a proximal end, a light delivery paththerethrough, and a light collection path therethrough, the fiber opticprobe comprising: a window disposed at the distal end of the lenscollection filter, the window having a distal end and a proximal end; alens disposed near the proximal end of the window, the lens having adistal end and a proximal end; an alignment feature having an aperture,the alignment feature being affixed to the lens; a light deliveryoptical fiber having a distal end and a proximal end, the distal endpassing through the aperture defined in the alignment feature; and acollection optical fiber in optical communication with the lens andwindow.
 12. The fiber optic probe according to claim 11, furthercomprising a lens collection filter disposed between the window and thelens, the lens collection filter having a distal end and a proximal end.13. The fiber optic probe according to claim 11, wherein the lens is atleast one of refractive, reflective, or totally internally reflective.14. The fiber optic probe according to claim 11, further comprising afiber collection filter disposed between the lens and the collectionoptical fiber, the fiber collection filter having a distal end and aproximal end.
 15. The fiber optic probe according to claim 11, whereinthe collection optical fiber is provided in a multi-ring arrangement.16. The fiber optic probe according to claim 15, wherein the multi-ringarrangement includes an inner ring and an outer ring, wherein the innerring corresponds to a first depth measurement and the outer ringcorresponds to second depth measurement, the first depth measurementbeing greater than the second depth measurement.
 17. The fiber opticprobe according to claim 11, further comprising a core tube that isfriction fitted into the alignment feature aperture.
 18. The fiber opticprobe according to claim 11, wherein the light delivery optical fiberemits laser light at or forward of the distal end of the lens.
 19. Thefiber optic probe according to claim 11, further comprising an emissionfilter disposed at a distal end of the light delivery optical fiber. 20.The fiber optic probe according to claim 11, further comprising a windowblock provided at the distal end of the window, wherein the window blockrestricts a surface area of the window.